原题
设计一种方法，从无序链表中删除重复项。
样例
给出 1->3->2->1->4. �返回 1->3->2->4
解题思路
- 遍历链表，用一hash表记录出现过的节点的值，如果出现过则删除，未出现过则加入hash表
完整代码
"""
Definition of ListNode
class ListNode(object):
def __init__(self, val, next=None):
self.val = val
self.next = next
"""
class Solution:
# @param head, a ListNode
# @return a ListNode
def removeDuplicates(self, head):
# Write your code here
if not head:
return head
res = head
map = {}
map[head.val] = True
while head.next != None:
if head.next.val not in map:
map[head.next.val] = True
head = head.next
else:
head.next = head.next.next
return res
